MortHump: Measure the Young Adult Mortality Hump

Fit diverse models of mortality graduation, parametric or not, in
order to isolate the hump that is often observed in the age-specific death rates
during adolescence and early adulthood in human populations. Can handle either
all-cause or cause-specific data. A description of the methods used can be found in Remund A., Camarda C. and Riffe T. (2018) Analyzing the Young Adult Mortality Hump in R with MortHump. MPIDR Technical Report TR-2018-3.